An I.C. (integrated circuit) device is formed by an I.C. chip capsulated within a resin package, as by a molding operation, and the chip connects to a plurality of pins (generally referred to as "leads") which project outwardly beyond the sides of the resin package. These leads are part of a lead frame which is generally elongated so that several such I.C. devices are formed longitudinally in spaced relationship therealong, with the I.C. devices thereafter being severed from the longitudinally extending edge strips of the lead frame.
As is well known, the leads are typically coated with solder, with the coating generally occurring in one of two different ways. In a first common technique, each I.C. device is separated from the lead frame, its leads are then bent downwardly substantially at right angles, and the bent leads are then dipped into a bath of liquid solder. The second conventional technique involves maintaining the plurality of I.C. devices integrally connected to the elongate lead frame so as to define a relatively flat package having a plurality of I.C. devices thereon, with this package in its entirety then being dipped into a bath of liquid solder.
The above techniques are known to possess several disadvantages. In an attempt to improve thereon, the Assignee of this invention has developed an apparatus for permitting solder coating of solely the leads while maintaining a plurality of I.C. devices connected to a common lead frame, such apparatus being illustrated by copending application Ser. No. 100,189, filed Sept. 23, 1987 now U.S. Pat. No. 4,836,131.
Accordingly, the present invention relates to improvements with respect to an apparatus for solder coating of leads associated with a plurality I.C. devices as mounted on a common lead frame.
In the improved apparatus of this invention, a pair of solder coating rolls are urged inwardly toward one another to define a gap through which the lead frame passes to permit simultaneous coating of opposite sides of the leads. The rolls are urged against an adjustable stop arrangement to define a gap therebetween which is adjusted to slightly exceed the width of the lead frame so that the solder coating on the rolls will automatically center the lead frame between the rolls and ensure application of a desired thickness of solder. At the same time the rolls drivingly move the lead frame through the gap. The rolls are mounted in cantilevered fashion from a pair of pivotally-mounted supports, which supports have counter-rotating meshing drive gears associated therewith at the pivot axes to drive the rolls.
Other objects and purposes of the invention will be apparent to persons familiar with apparatus of this general type upon reading the following specification and inspecting accompanying drawings.